Bulletin No. 44 



U. S. DEPARTMENT OF AGRICULTURE 

DIVISION OF CHEMISTRY 



SB 



SWEET CASSAVA: 



ITS CULTURE, PROPERTIES, AiND USES 



SY 



HARVEY W. WILEY 
Chemist of i?he U. S. Department of Agriculture 



PUBLISHED BY AUTHORITY OF THE SECRETARY OF AGRICULTURE 



WASHINGTON 

GOVERNMENT PRINTING OFFICE 
1894 



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Book__^Jl_3\Y^ 



Bulletin No. 44 



U. S. DEPARTMENT OF AGRICULTURE 

DIVISION OF CHEMISTRY 



SWEET CASSAVA: 

ITS CULTURE, PROPERTIES, AND USES 



BY 



HARVEY W. WILEY 
Chemist of thk U. S. Depaktmekt of Agricultuke 



PUBLISHED BY AUTHORITY OF THK SECKETAKY OF AGRICULTURE 



WASHII^GTOK 

GOVEKNMENT PRINTING OFFICE 
1894 



T] 






%^^ 



N(^l^ 



LETTER OF TRANSMITTAL. 



U. S. Depaktmkxt of Agriculture, 

Division of Chemistry, 
IVasMnfjton, D. C, September 15, 1894. 

SiH: I beg to submit for yonr insppotion and approval the manuscript of Bulletin 
No. 44, giving a description of our investigations of the agricultural possibilities 
of sweet cassava. 
Respectfully, 

H. W. Wiley, 
Chief of Division. 
Hon. Charles W. Dauney, Jr., 

Act'iny Secretary of AgricuJiure. 



CONTENTS. 



Page. 

Distribution — names — varieties 3 

Cassava as an article of food 4 

Analysis of cassava roots, exclusive of bark 4 

Analysis of cassava flour 5 

Extracts from correspondence 6-8 

Analysis of root and bark, each separately 9 

Comparison of cassava starch with Indian corn starch 10 

Composition of the ash 12 

Methods of culture 13 

Conclusions 16 

9 



SWEET CASSAVA: ITS CULTURE, PROPERTIES, AND USES. 



DISTRIBUTION — NAMES — VARIETIES. 

In the southern peninsula of Florida, and growing up well into the 
frost belt, is found in many localities a cultivated plant known as 
cassava, or sweet cassava. From a careful study of the climatic con- 
ditions under which the plant flourishes it is safe to assume that it may 
also be grown with success in southern Alabama, Mississippi, Louisiana, 
and Texas. Cassava is a name which should properly apj^ly only to the 
purified starch derived from the roots of the plant, but it has passed 
into general use to designate the plant itself. Botanically, the plant is 
known as Janipha inanihof, Manihot ntilissima,, Jatropha nianihot, Man- 
ihot a'ipi,, Manihot loeJ!inf/ii, and Manihot palmata. One of its common 
names is manioc plant. The fleshy root of this plant yields the greatest 
portion of the daily food of the natives of many portions of tropical 
America, and one of its forms of starch is iinj)orted largely into this 
country as tapioca. It is a woody or shrubby plant, growing from 
fleshy, tuberous roots, the stems being smooth, with nodules where the 
leaves grow. 

There is properly only one variety of the plant growing in Florida, 
while that, variety which grows in the tropics contains so much hydro- 
cyanic acid as to render it poisonous. The variety grown in the sub- 
tropical region of Florida, however, contains only a small quantity of 
hydrocyanic acid, and is therefore commonly known as sweet cassava. 
Some of the growers of the plant in Florida claim that two varieties 
grow in the State, one of which is poisonous on account of the large 
amount of hydrocyanic acid ^yhicll it contains, and the other nonpoison- 
ous, containing only a little hydrocyanic acid. It is quite probable, 
however, that after the poisonous variety has grown for a long while 
in a subtropical climate it would lose largely its i)oisonous properties. 
The leaves of the poisonous variety in the trojDics usually have seven 
branches palmately divided. The leaves of the sweet variety are usually 
only five-parted. The botanists clearly recognize two distinct varieties. 
For instance, in the "Treasury of Botany," page 718, the following 
remarks are made: 

It is quite clear that while the root of one ia bitter and a virulent poison that of 
the other is sweet and wholesome, <iud is commonly eaten cooked as a vegetable. 
Both (if them, especially the bitter, are most extensively cultivated over the greater 

3 



part of tropical America aud yield aii abuudauce of wholesome and nutytious food 
the poison of the bitter kind being got rid of during the process of preparation it 
undergoes. The poisonous, expressed juice, if allowed to settle, deposits a large 
quantity of starch known as Brazilian arrowroot or tapioca meal, from which the 
tapioca of the shops is prepared by simx)ly torrefying the moist starch ujion hot 
plates, the heat causing the starch grains to swell and burst and become agglutinated 
together. A sauce called cassarecp, used for flavoring soups and other dishes, partic- 
ularly the West Indian dish known as pepper pot, is also prepared from this juice by 
concentrating and renderiug it harmless by boiling. Another of the products of 
cassava is an intoxicating beverage called piwarrie, but the manner of preparing it 
is not calculated to render it tempting to Europeans. It is made by the women who 
chew cassava cakes and throw the masticated materials into a wooden bowl, where 
it is allowed to ferment for some days, and then boiled. It is said to have an agree- 
able taste. 

CASSAVA AS AN ARTICLE OF FOOD. 

The- atteutiou of the Division of Chemistry was first called to the 
cassava plant as au article of food and a possible source of starch, in 
1888, in a letter received from Mr. R. H. Burr, of Bartow, Fla. Mr. 
Burr also sent a package of cassava roots. He described the plant 
and its uses in the following words : 

The roots do not last long after digging, dryiug up, or rotting. Since this variety 
of cassava is not the bitter or poisonous kind, it is generally known in Florida as 
the sweet cassava. The roots are fed to all kinds of stock in a fresh state, aud are 
greatly relished. It has been sufficiently tested here to show its great value as a 
stock food. The yield under favorable conditions is astonishing. I have recently 
dug one plant of one year's growth which weighed .50 pounds, being at the rate of 
more than 1,500 bushels to the acre. Eight hundred to 1,000 bushels per acre cau be 
confidently reckoned on. 

The roots received by us were long and slender and of various sizes; 
some of them were quite 2 feet long, and weighed several pounds. The 
analysis of the sample, exclusive of the bark, calculated to dry sub- 
stance, is given in the following table : 

Serial number 5547 

Ash per cent.. 1. 94 

Oil (petroleum ether extract) do.. .. 1. 27 

Ether extract (resins, alkaloids, organic acids, etc.) do 74 

Alcohol extract (aniids, sugars, gliicosids, etc.) do 17.43 

Crude fiber do ... . 4. 03 

Starch do .... 71 . 85 

Albuminoids (calculated from nitrogen) do 3. 47 

100. 73 

In regard to the method of analysis little need be said ; it was carried 
on in accordance with tlie well-established rules of i)lant analysis, as 
laid down by Dragendorff. The first extraction of petroleum ether 
gave the fat or oil alone, and the subsequent extraction Avith sulphuric 
ether gave the resins, alkaloids, and organic acids. That portion of 
nitrogen existing as amids was estimated in the alcoholic extract. 
The total nitrogen was also estimated and entered as albuminoids j a 



small portion of the nitrogen has thus been counted twice in the total 
results, which add up a little over 100. A characteristic feature of the 
cassava root is shown in the large amount of substance Dresent, solu- 
ble in alcohol. The amount of starch also compares fairly well with 
the best varieties of potatoes. On account of the large quantity of 
sugars present, the cassava root could be more economically used for 
the manufacture of glucose than for starch. There is no doubt, how- 
ever, of the fact that a tine article of starch for the laundry or for food 
can be made from the cassava root growing in this country. 

In addition to tlie fresh root above noted, two samples of the dried 
root or cassava meal have also been examined. No. 5922 was sent to 
us, described as pulverized manihot root or cassava flour. The root is 
first peeled, chopped into thin slices, dried in the sun two days, and 
pulverized. It was prepared by Prof. W. H. Kern, of Bartow, FJa. 
1^0. 5023 was labeled pulverized cassava, with the starch, or a portion 
of it, and glucose washed out, the remaining pulp dried in the suuj 
prepared by Prof. Kern. 

Prof. Kern sent a letter with the samples, from which the following 
extracts are made : 

Allow me to say that, owing to the prodigious yield per acre of what we here know 
as cassava and its alleged value as a feed and food jilant and for its yield of starch and 
glucose, it is attracting a very great deal of attention here now. The plant here grown 
is different from the manioc root of South and Central America; our root contains 
no poisonous elements which need to be dissipated by heat. It is customary here, 
for many persons to make their own starch from it. The root, which must remain 
in the ground until one is ready to use it, is dug, washed, and its two inner and 
outer x>eelings removed; it is then grated and the pulp washed, the water poured 
off in a vessel and allowed to stand, when the pure starch settles in the bottom. The 
clear water is again drawn off and the starch allowed to dry. The pulp, after 
having the stnrch washed out, may be used at once in making puddings by the 
addition of milk, eggs, etc. This washed pulp may be sun-dried and thus kept, 
forming valuable meal or Hour, from which nice bread may be made. Necessitated 
as we are in south Florida to buy all our wheat flour, anything which acts as a sub- 
stitute, either in whole or in part, is of great value to us. 

The analyses of two samples of flour are given in the following 
table : 

Serial number 5922 5923 

Water per cent.. 10.56 11.86 

Ash do.... 1.86 1.13 

Oilandfat do 1.50 .86 

Resins, alkaloids, and organic acids do 64 .43 

Amids, sugars, glucosids do 13.69 4.50 

Dextrin, gum, etc., by difference do 2.8.5 5.63 

Crudefiber do 2.96 4.15 

Nitrogenous bodies do 1.31 1.31 

Starch do.... 64.63 70.13 

From the above analyses it is seen that the cassava can never take 
the place of the flour made from cereals as a food material on account 
of the small portion of nitrogenous matter which it contains. It seems 



to me, however, that it might very well take the place of potatoes, and 
its value as a food should not be underestimated. 

In order to get further information in regard to the growth and uses 
of cassava in Florida, a circular was sent to as many addresses as could 
be obtained of persons interested in its growth in that part of the State 
suited to its culture. This circular asked for information in regard to 
the time and method of i)lanting, method of cultivation, kind of soil 
and fertilizers, proper time for harvesting, length of time the roots can 
remain in the ground, the effect of frost on the plant, the yield of roots 
per acre, their value as food, method of preparing for food and starch, 
profit of cultivating, and the certainty of the crop. In all, about three 
hundred answers were received to these questions. Some of these 
answers stated that the crop was not grown in the part of the State 
from which they were written. A few of tlie replies were unfavorable 
in regard to the utility and value of the crop. Nearly all of them, 
however, represented that the crop was a certain one, extremely valu- 
able, and the roots an excellent food for man and beast. 

Many of the correspondents give rather full notes in regard to the 
value of the crop and the localities in which it grows. In Florida it 
seems to flourish in almost every part of the State. 

Mr. J. B. Pixton, of Ellerslie, Pasco County, writes: 

I found it growing profusely in Taylor County, this State, some yaars since. Tbe 
roots were thicker than a man's arm and about 4 feet long. The settlers almost live 
" on it. ' 

Taylor County is in the northwestern part of the State, bordering on 
the Gulf. The same writer says that in his locality it did not do so well 
and that he could make nothing of it. 

Prentice Bailey, in an article in the Tropical Sun of February 9, 1893, 
published in Juno, Dade County, says: 

I consider it superior to any root crop grown in this country. It is very produc- 
tive; it has a remarkable immunity from drought, ilood, and disease; it is easy to 
harvest, easy of cultivation, and occupies tho ground during the whole growing 
season to the exclusion of noxious i)lauts. The pork made from feeding it is solid 
and delicate as chicken, and the lard is as tirni as that of corn-fed hogs. It produces 
a good flow of rich milk and a firm, golden butter. From 1 acre of cassava enough 
roots may be obtained to fatten 10 hogs or feed 3 milch cows during the entire year- 
Mr. Bailey states that in his opinion it can be grown as far north as 
Atlanta, Ga., in which opinion, however, I am unable to concur, as pre- 
ponderating testimony goes to show that the plant will not do well in 
localities subject to heavy frosts. 

Mr. Fred W. Inman, of Winter Haven, Polk County, says: 

There is no better food for stock, especially during the winter months. I have fed 
my cows, mules, horses, hogs, and poultry upon it everj^ season for the past six 
years. It fattens better than corn. Tliero is nothing grown in this country that 
can compare with it. It has no enemy but fro.st. I esteem this crop one of the most 
essential as well as profitable that the Florida farmer can grow. It furnishes- food 
for my stock, poultry, etc., for about nine months in the year. 



Mr. Sherman Adams, in the Florida Agricnlturist, says: 

Soil suitable for corn is appropriate for cassava. It must not, however, be wet 
land or land subject to overflow, as that will rot the tubers. Frost, if severe, will 
kill the plant so effectually that but a small proportion will sprout again. By sav- 
ing the stumps when tlio roots are dug, and planting them, they will sprout and 
grow, though the tops be killed two or three times. There are about 2,740 hills per 
acre. On land that will not grow more than 5 bushels of corn per acre, cassava 
will average from ^ to 5 pounds per hill, or, at a very moderate estimate, 4 to 5 
tons per acre. 

Mr. S. W. Carson, of Midland, Polk County, says: 

There is but one variety of cassava, viz, the sweet kind, gfown in Florida. I have 
never seen any sample of the bitter variety. A Spaniard who was once conversing 
with mo on the subject of cassava gave his idea as a proper definition of cassava 
as "the life of man." After cultivating the plant for a quarter of a century, I am 
ready to agree with him. If judiciously used it will reduce the grain rations for 
horses and mules at least one-half. For cows you may keep bits of it mixed in the 
slops and other food. I have never cooked it for stock, as I believe it is best fed raw. 
In feeding to fowls, it should be thrown into the yard in its raw state daily, but in 
small quantities. After feeding on it for one mouth any fowl will be fat enough to 
cook without lard or butter. Honey bees forage largely on the blooms; cattle eat 
with relish the tender shoots. The finest fowl yard imaginable could be made in a 
cassava patch by turning the fowls into the patch ten mouths after ]»lanting. The 
roots would supply them with food and the tops shelter them from the sun. 

1 regard the rolling pine lands, containing some willow oak, to be the best for 
cassava, and the southern counties to be best suited to it. Let the soil be well pre- 
pared by plowing and harrowing, rows checked about 4 feet apart, and one piece laid 
in each hill. I think they should never be closer together than 4 feet, and 5 would 
be better. Cassava has been known to grow for three years in this country. It will 
continue to grow until the cold kills it; then, by breaking oft' the stems when they 
are red, the stubble will sprout up in the spring. As to the seeds of the cassava, 
they will ripen in about one year. If puddings, custards, etc., are desired, the roots 
must be peeled and grated; salt, sugar, etc., may be used according to taste. The 
Spaniards make bread of it simply by grating the root, and adding salt and a little 
soda. Now, there is no doubt in iny mind but that 30 tons of cassava root per acre 
can be produced. When I think of the tapioca, glucose, and starch there are in it, 
and how abundantly it can be turned into bacon and lard, ndlk and butter, mutton 
and beef, I feel confident that it will pay better than any other plant in the world. 

Mr. Paul Dupuy, of Boardman, Marion County, says but little cassava 

is grown in that locality: 

Some months ago I spent fourteen months in Brazil, where the mandioc plant is 
generally used as food by man and beast. In truth, it constitutes the bread of the 
country, being a general article of food for all classes. It is prepared for food in 
Brazil by grating it into a coarse pulp and pressing it to get rid of as much of the 
juice as possible, which contains a large proportion of hydrocyanic acid. The pulp 
is then placed in shallow copper pans and thoroughly dried over a gentle fire. In 
this condition it resembles corn grits, and it is eaten in this shape, or it can be 
cooked and jirepared as corn meal and other starchy products. The sediment from 
the expressed juice, when dried, constitutes the tapioca of commerce. As a starch 
product I do not think it can be excelled, because of its enormous product per acre. 

Mr. A. Stephens Means, of Johns Pass, Hillsboro County, says : 

It has great value as stock food, being very rich in starch, and most animals eat 
it greedily. It is a nourishing food for man and can be used in a number of ways, 
as a substitute for potatoes, or the starch may be extracted and used for puddings, 
etc. Any soil suitable for potatoes cau be used for cassava. 



Mr. M. K. Lyman, of Lautana, Dade County, writes : 

I have no success with cassava. I have made several efforts to raise tBe plant and 
have failed in every case. I have splendid success ■with tanyah, or taro. It makes 
a substitute for the potato all the year, being an evergreen, yielding edible roots the 
year around. 

Mr. William Fisher, of Clay County, says: 

I doubt very much if cassava ever supplants the sweet potato as human food, for the 
Southerners like the sweetness of the potato and it can be cooked in one-third the 
time required for cassava. But as stock feed I believe the cassava is well worth a 
trial. lu my judgment, the planting, cultivation, and harvesting of it would involve 
less labor than the potato; the seed is as easily wintered; the crop can be left in the 
ground all winter, and it yields more per acre than the potato and is apparently 
equal to it in nutritive value. 

Mr. Stephen Powers, editor of the Florida Dispatch, says: 
The plant is indigenous to the West Indies and to Africa. In the West Indies it 
is known as cassava, while in South America it is commonly known as mandioca, or 
mauioca. The name yucca, which some people insist on giving it, is a clear mis- 
nomer, since the yucca belongs to the LiUacew, or lily family, while the cassava 
belongs to the Eiq^horhiacew family. The plant was eaten by the South American 
and Caribbean Indians centuries before this hemisphere was discovered by Euro- 
peans. Southey says of it : " If Ceres deserved a place in the mythology of Greece, 
far more might the deification of that person have been expected who instructed his 
fellows in the use of mandioca." In Brazil, in the form of coarse flour, a majority 
of the population use it the year round in lieu of bread. A mild intoxicant is also 
distilled from it which is the universal drink of the lower classes. The South 
American Indians use the following formula for manufacturing cassava beer: The 
roots are sliced, boiled till soft, and cooled. They are then chewed mouthful by mouth- 
ful, the masticated cuds being returned to the vessel. [This process, although not so 
stated in the description, is evidently intended to transform the starch into sugar 
by the act'on of the saliva.] The jar is then filled with water and boiled for several 
hours with constant stirring. The liquid is then poured off into another j ar, half 
buried in.the dirt floor of the hut in which the family lives, closely covered, and 
allowed to ferment two or three days. When required for use a fire is built around 
it, and the l)everage is served steaming hot. It is not as palatable for human food 
as sweetipotatoes, and to expect therefore to substitute cassava for either the sweet 
or the Irish potato would be a step from a higher to a lower civilization, but as a 
food for%live stock it has a great superiority. It is worth at least 25 per cent more 
than sweet potatoes to produce milk or fat. With no more manure, and loss culti- 
vation than is required for Indian corn, it will produce an amount of feed worth at 
least four times as much for fattening animals aud incomparably more for producing 
milk. It is easier toj)lant and cultivate than sweet potatoes, but harder to dig, so 
it maybe called even on this score. With the same manuring it will yield 600 
bushels per acre, while sweet potatoes will yield only 500. 

Mr. J. H, Moore, of Keuka, Fla., in a letter to the same paper of 

November 24, 1887, describes some of the uses of cassava. From his 

letter the following extract is made: 

Cut the stalks about 1 inch above the ground, just before frost; after cutting, the 
stalks should bo left to dry in a cool place a few weeks, and then placed in a trench 
and covered until time for planting. Some save the stalks by keeping them in a dry, 
cool place until February and then planting. The roots should be dug as used ; they 
will not keep in good condition out of the ground more than three or four days. It 
is perhaps the best feed we can raise for hogs; it is also a fine feed for poultry. We 
often bake it like sweet potatoes, aud als© slice and fry it like Irish potatoes. 



9 



M, Sacc has addressed a letter to the National Society of Agriculture 
of France concerning the cassava, which he calls Manihof nUlissima. 
He is of the opinion that the poisonous varieties are different botan- 
ically from the iHinocent. Manihot is the bread of tropical regions. The 
innocent variety is cultivated in Bolivia, and the botanists there call it 
Manihot dipi. The plant grows from 1 to 2 meters in height, with 
straight and naked stalks, since they only develop leaves at their 
extremities; the only care given to them in their cultivation is to keep 
them free from weeds. The roots, to the number of five to nine, are of 
the size of the closed hand. The following analysis of the roots of the 
Manihot aipi is given: 

Per cent. 

Water 70.29 

Starch 14.40 

Sugar, salts, and malic acid 1.01 

Fibrin and yellow coloring matter 08 

Crude fiber 3.16 

Ash 10.82. 

From the above it is seen that the roots of the tropical plant are quite 
different from those produced in our own country. In regard to the 
distribution of the two varieties, M. Sacc makes the following observa- 
tion : 

In Cuba I have seen only the jioisonous variety. The same is true of Brazil, where 
I have not seen the Manihot dipt except in the Swiss colony, Porto Real. As to the 
product of the two varieties, it is the same; the stalks, which are the size of the 
finger, are from 1 to 2 meters in height. I have not been able to analyze the leaves 
of this interesting A^egetable, but as they are much sought after by cattle they are 
probably very nutritious. 

These interesting facts concerning the cassava plant, derived from 
our own analyses and observations and from the correspondence noted 
above, have led us to believe that a wider knowledge of the properties 
of this interesting plant would prove of interest not only to the growers 
thereof, but also to capitalists and manufacturers, who might be inter- 
ested in it as a promising source of food and as the raw material for 
the manufacture of starch and glucose. 

A large quantity of the root, therefore, was obtained from Florida, 
the bark separated from the root, and each subjected to analysis with 
the following results : 





Peeled root. 


Fiber 

after 

removal 

of starch. 


Bark of root. 




Fresh. 

Per cent. 

61. 30 

.17 

.64 

30.98 

88 

.51 

5.52 


Dry. 
Per cent. 


Dry. 


Fresh. 


Dry. 


Moisture 


Percent. 


Per cent. 

61.30 

.66 

2.29 


Per cent. 


Ether extract 


.44 
1.66 

80.06 
2.26 
1.31 

14.27 


.30 

1.02 

64.64 

10.68 

1.42 

21.94 


1.70 


Albuminoids (mtrogeu ,\ 6.35) 


5.91 


Starch (diastase-extract inverted with HCI) 




Fiber 


3.83 

2.02 

29.90 


9.89 


Ash 


5.23 


Undetermined 


77.27 








100. 00 


100. 00 


100. 00 


100. 00 


100. 00 



10 

With the starch in the analysis given above is reckoned also the solu- 
ble carbohydrates, consisting almost exclusively of cane sugSr, and of 
which, in an analysis«of another portion of the dry substance, as high 
as 17 per cent were found. In the laboratory it is not difficult to pre- 
pare crystallized cane sugar from the aqueous extract of the fresh pulp. 
We have made such a preparation. The percentage of sugar iu the 
plant, however, Istoolow to excite anyreasonable hope of the preparation 
of this. article ou a commercial scale. The most promising way to save 
it is by conversion into glucose, as indicated in another place. The 
undetermined portion consists of the digestible fiber and carbohydrates 
of the pentose series. The i^entosans in the fiber were determined by 
the furfurol process, as modified by Krug, and the amount in the air. 
dried material was found to be 3.92 per cent, and iu the material after 
the removal of the starch 5.33 jier cent. 

The fresh root was found to contain 38.7 per cent of dry matter, being 
considerably more than was found in the fresh sample of the previous 
analysis. Of this 38?7 per cent, 30.98 consisted of starch and soluble 
carbohydrates. 

Experiments were made to determine the yield of air-dry starch which 
could be obtained from the roots by laboratory work. Two sets .of 
experiments were made. In the first set the roots were pulped on a 
Pellet rasp, used for i)rei>aring beet pulp for instantaneous diffusion. 
Twelve kilos of the unpeeled root were rasped in this way and the starch 
separated by washing through a sieve of bolting cloth. The.washings 
and settlings were collected and dried. in. the ordinary method of starch 
manufacture. The yield of pure starch was 3,105 grams, equivalent to 
25.9 per cent of the total weight of the root. The starch was almost 
absolutely pure, containing only a trace of nitrogenous. matter. In the 
sec.ond experiment 10 kilos of the root were ground in a pulping machine, 
used for preparing green fodder for analysis. The pulp was much less 
fine than that produced by the Pellet rasp. Trea.ted in the. same way, 
the yield of air-dry starch was 2,360 grams, or 23.6 per cent. One of the 
striking points in connection with the work is that the residue from the 
starch, which consisted largely of fiber, as will be seen by reference to 
the above analysis, contained still a large percentage of starch, show- 
ing that by the process employed the whole of the starch was not 
secured from the pulp. The diameter of the starch granules is a little 
over 0,01 mm,, being about seven times smaller than the average of 
potato starch. 

COMPAKISON OF CASSAVA STARCH AND INDIAN CORN STARCH, 

The illustrations given are from photomicrographs of the starch 
granules, which, for purposes of comparison, are accompanied by illus- 
trations of the finest pre])ared Indian-corn starch. 

Fig. 1, Plate i, shows the granules of cassava starch in plain light, 
magnified 150 diameters. 



11 

Fig. 2, Plate i, shows Indian corn starch in siniihir conditions. The 
average size of the jiarticles is the same in both instances, viz, 0.012 mm- 
The cassava particles are more irregnlar in size, and are, moreover, to 
be distingnished from the maize particles by greater evenness of ont- 
liue. The cassava, however, more nearly resembles the maize starch 
than it does any other well-known variety, and by reason of this resem- 
blance conld easily take the i^lace of maize starch in the kitchen and 
laundry. 

Fig. 1, Plate ii, shows cassava starch magnitied 150 diameters and 
viewed by polarized light. Only the larger particles are well in focus, 
nevertheless the cross can be seen on the smaller by close inspection. 

Fig. 2, Plate ii, shows maize starch in similar conditions. While it 
would be difficult in all cases to distinguish these two starches by the 
microscope, yet there are some points of difference, as have already 
been noted, by means of which the expert may usually be successful in 
the discrimination. 

The cassava which grows in tropical regions contains a notable per- 
centage of hydrocyanic acid, so great, in fact, that it can not be used 
directly as a food. The so-called poisonous cassava is boiled, to expel 
the hydrocyanic acid before being used for feeding purposes. A care- 
ful determination was made of the hydrocyanic acid in the fresh root 
and the amount was found to be in considerable quantity, but not suf- 
liciently large to be alarming. Nevertheless, any possible danger could 
be avoided before using the material as a food by subjecting it to a 
sufficient heat to expel the hydrocyanic acid. The hydrocyanic acid 
seems to be distributed throughout the pulp, and particularly in the 
juices which can be expressed from the pulp. jSo injurious effect from 
the hydrocyanic acid has ever been observed in the case of animals fed 
on cassava in Florida. 

The bark of the root was also subjected to analysis, as will be seen 
by reference to the following table. It contained no starch, the unde- 
termined matter being chieily digestible fiber and pentosans. 

The mineral matters extracted from the soil are distributed as indi- 
cated in the table. The amount of ash in the root itself is quite low, 
showing that the cassava plant does not require a soil very rich in 
mineral constituents. The amount of mineral matter taken from the 
soil by 100 kilos of the fresh root is approximately only half a kilo. 
The albuminous matters are also present in small quantities, being 
only slightly larger in weight than the ash itself. The i)lant, therefore, 
is one which seems particularly suited to feed almost exclusively from 
the air and water, and hence is one which could be recommended on 
the sandy soils of Florida as a crop which would require the minimum 
of fertilization. 



12 

COMPOSITION OF THE ASH. 

The ash of the peeled, root aud the bark of the root was subjected to 
analysis, with the following results : 

Analysis of the ash of cassava root. 



Constituents. 



Carbon 

Silica (Sdluble in solution of Na5C03) . 
Silica (insoluble in solution ot Na2C03) 

Ferric oxiil ( lejUj) 

Calcium oxid (CaO) 

Magnesium oxid (MgO) 

Sodium oxid (Na.,( )) 

Potassium oxid (K.;0) 

Phosphoric acid ( PaOs) 

Sulphuric acid (SO3) 

Carbonic acid (CO2) 

Chlorin (CI) 

Total 

Oxygen equivalent to chlorin 

Difference 



Peeled root. 



A. 



Per et. 

0.30 

0.97 

7. 15 

0.66 

10.63 

7. 3C 

1.12 

41.72 

15.58 

3.67 

9.15 

2.76 



B. Mean. 



Per ct. 

0.31 

91 

7. 1.") 

0.66 

10.64 

7.35 

1.28 

41.54 

15.59 

3.80 

9.12 

2.75 



101.07 
0.62 



101.10 
0. 62 



100. 45 



100. 48 



Per ct. 

0.31 

0.94 

7.15 

0.66 

10.04 

7.35 

1.20 

41.63 

15.58 

3. 73 

9.14 

2.75 



101. 08 
0.62 



100.46 



Bark of root. 



A. 



Per ct. 

0.79 

10. .53 

52. 99 

2.46 

6.58 

3.31 

0.84 

14.73 

2.44 

1.71 

2.53 

1.41 



100. 32 
0.31 



100. 01 



B. Mean. 



Per ct. 

0.77 

11.30 

52. 16 

2.44 

6.65 

3. 33 

1.05 

14.68 

2.46 

1.71 

2.50 

1.42 



100. 53 
0.31 



100.22 



Per ct. 

0.78 

10.94 

52.58 

2.45 

6.62 

3. 32 

0.95 

14.70 

2.45 

1.71 

2.51 

1.41 



100.42 
0.31 



100.11 



From the above numbers it is seen that the ash of the peeled root is 
especially rich in potash, almost one-half of the total weight being com- 
posed of this substance. The potash is combined chiefly with carbonic 
and phosphoric acids. In the ash of the bark, as might be expected, 
silica IS the predominant element, more than half the total weight con- 
sisting of this substance. 

Assuming a yield of 5 tons of roots per acre, the weights of the 
important fertilizing materials removed by such a crop can be readily 
calculated from the data given. 

Since the bark forms approximately 2.2 ])er cent of the entire root, 
the total crop would be made up of the following amounts of bark and 
peeled root which would contain the amounts of mineral matter given 
below : 



Peeled root . . 
Bark of root . 



Pounds. 



9,780 
220 



Pounds 
of ash. 



49.88 
4.44 



10, 000 



54.32 



The more important mineral matters contained therein are: 



Lime (CaO) 

Magnesia (MgO) 

Pota.sh (KjO) 

Phosphoric acid (P2O5) 

Re.sidue 



Ash from 

l)eeled root 

(49.88 

pounds). 



Pounds. 
5.31 
3.67 
20.77 

7.77 



12.56 



Ash from 

bark (4.44 

pounds). 



Pounds. 

0.29 

.15 

.65 

.11 



3.24 



Total ash 

from 5 tons 

(54.32 

pounds). 



Pounds. 
5.60 

3.82 

21. 42 

7.88 



15.60 



13 



The less valuable mineral plant foods, that is, those that are of so lit. 
tie note as to recinire no conservation or addition, amount to 15.60 
pounds per acre and the more valuable to 32.72 pounds iter acre. 

Quite a number of preparations was made from the starch of tlie root, 
and amony- them may be mentioned : First, tapioca; the first portions 
of starch washed out, especially, produce an excellent article of tapioca 
when treated in the usual way. Second, glucose; both the fresh root 
and the extracted root yield full theoretical amounts of glucose, and 
samples of this article were made by the conversion of the starch both 
by sulphuric acid and diastase. The samples of glucose made from the 
starch were exceptionally good, especially when diastase was used, 
the glucose in this case containing large quantities of maltose. Com- 
mercially it would be more profitable to make the glucose directly from 
the fresh root, in which case the considerable percentage of cane sugar 
contained by it would be saved, whereas if glucose be made from the 
starch the cane sugar is previously washed out. On account of the 
presence of the bark, however, the glucose nmde from the whole root 
is not so tine in quality as that made from the pure starch. Third, 
alcohol; the glucose on fermentation affords the usual quantity of 
alcohol. Fourth, cane sugar; a beautiful preparation of cane sugar 
was made from the water used in washing out the starch. The amount 
of cane sugar, however, is not large enough to warrant its extraction 
on a commercial scale from the waters used for washing. It is, how- 
ever, present in sufticient quantity to indi- 
cate that in making glucose it is better to 
use the whole root as indicated above. 

The general result of the analytical 
work is such as to establish the fact that 
the cassava is a plant of high economic 
value and worthy of the attention of those 
interested in the carbohydrate products 
of the country. 

METHODS OF CULTURE. 

Cassava has been grown for one year 
on the Department Experiment Station 
at Runnymede (post-office, Narcoossee), 
Osceola County, Fla. The crop was 
grown as food for stock. The field in 
which the crop was grown is high pine 
sand, with almost no other ingredient. 
The illustration of the cassava given here- 
with is from a photograph of a plant 
taken from a field near the station. The fig. i. 

soil on which it was grown was apparently pure sand. It represents the 
larger plants in the field, but not by any means the largest. The illus- 
tration (fig. 1) shows in a striking manner the stem and root develop- 




14 

ment. This plant, of wliich the photograph is given, was 5 feet high. 
The roots in the soil occupy a more nearly horizontal f>osition than is 
shown in the figure. The thickened part of the stem to which the roots 
are attached, represents the cutting from wliich the plant grew. 

Attempts were also made to grow the cassava in a piece of very wet 
muck land on the station in which sugar cane would not grow to any 
advantage. An immense development of tops was secured, some of the 
plants reaching a height of 10 feet and resembling young trees. The 
root development was fair, but not commensurately increased with the 
top growth. Some of the stems were easily 2 inches in diameter. On 
well-drained muck land I think the crop would be large and profitable. 

In sand land the planting should be preceded by the removal of 
stumps, sprouts, etc., and the soil given a thorough plowing. It is 
advisable to spread about 300 pounds of fine raw Florida phosphate 
floats or about 150 pounds of superphosphate containing 12 per cent 
available acid, to the aci^e. This may be applied as a top-dressing and 
thoroughly worked into the soil by a deei3-running cultivator. The 
rows should be marked out in furrows 3 to 4 inches deep and from 3J 
to 4 feet apart. To get a good stand about double the number of cut- 
tings required to produce 2,500 hills per acre should be planted. The 
excess of plants can be removed by a hoe as soon as vigorous growth is 
assured, leaving one hill each 3 or 4 feet. About 150 pounds of kainit 
per acre should be dropped in the hills before planting, together with 
an equal amount of cotton-seed meal, or half that amount of Chile salt- 
peter (nitrate of soda). 

The cultivation should be such as to keep the field free of all weeds 
and the surface of the soil well stirred. While the plants are young 
deep cultivation is not objectionable, but as soon as the root system 
begins to develop, flat superficial culture must be practiced; not to 
exceed 2 inches in depth. Some cultivators draw the soil to the plant 
during cultivation so as to form a ridge at the timeof laying by. Where 
nitrnte of soda has been used an additional 50 or 75 pounds per acre 
should be sown broadcast Just before the final cultivation. The above 
method is the one which should be followed for the poorest kind of sand 
soils, where a maxinuim crop is desired. For muck soils, the cotton- 
seed meal and nitrate of soda should be omitted and about 500 pounds 
of Florjda phosphate floats used per acre. If sand soils are covered Avith 
a good layer of muck before the plowing the nitrogenous fertilizers 
may also be omitted or reduced in (juantity. ' 

In ordiiuiry seasons with the treatment outlined above, a crop of 
from 4 to 7 tons i)er acre will be secured. On sand soils containing a 
little organic matter ai)proaching the hammock variety, a fair yield of 
from 2 to 4 tons per acre will be secured by good cultivation without 
fertilizing. 

For seed, the stems of the unfrosted plants are cut into pieces about 
6 inches in length, care being taken that each i>iece has two or more 
eyes. In planting, these jjieces may be laid directly down in the fur- 



BuL. 44, Div. Chemistry. U. S. Dept. Agriculture. 



Plate I 




-up*^ (5 



Cassava Starch x iso. 

PLAIN ILLUMINATION. 



Fid 2 






<f 









^^% 
y%/ 



Q» 



© 



<^|^ 




ft © 

© 






O®^e0 



SO, 



e<^, 



Corn Starch x iso. 

PLAIN ILLUMINATION. 



A Hoen &Co...Lithocaustic 



BUL 44, Div. Chemistry, U. S. Dept. Agriculture. 



Plate 2. 



Fid 1 




Cassava Starch x iso. 

POLARIZED LIQHT. 



Fig 2 



«*■» 






Corn Starch x iso. 

POLARIZED LIGHT. 



A Hoen &Co..Lithocaustic 



1 



15 

rows and covered, but tlie general practice is to place them obliquely 
in the furrows so that one end may not be covered. In case of a threat- 
ening frost before a field is ready for planting the unfrosted tops may 
be cut, thrown into heaps, and protected with leaves or trash from the 
action of the frost. They should, however, be embedded in moderately 
moist earth if they are to be kept before planting for any length of 
time. In case of frost before the seed is saved the stumps, i. e., the 
points of union of the top with tlie root, will usually be found unin- 
jured, and these may be cut away and planted instead of the cuttings 
just described. The larger parts of the stems immediately above the 
ground make the best seed. 

The roots should be left in the ground until they are needed for use, 
whether for food, for starch, or for glucose. The croji can be harvested 
at any time during the year, but the best season is from October to 
May. The roots should not be allowed to grow more than two seasons, 
and for most purposes it is believed that an annual harvest will prove 
the more i^rofitable. 

As is the case with all new and promising plants, the most extrava- 
gant statements have been made in regard to the amount of cassava 
which can be produced per acre. In many of the returns received 
from our correspondents in Florida, statements were made in regard to 
the yield which were entirely beyond the bounds of reason. These 
extravagant statements, of course, did not proceed from any desire on 
the part of correspondents to misstate the facts, but on account of 
their misapprehension of them. Statements of yield are made as a rule 
not upon accurately measured and weighed products, but upon a mere 
glance over a field or the taking of a few hills. It is easy, therefore, for 
the most honest and upright correspondent to fall into gross error in 
regard to the amount which will be furnished by an acre. In my own 
observation of small areas and from the accredited statements of those 
authorities which seem to merit the highest consideration, I am con- 
vinced that on the ordinary pine land of Florida, with proper prepara- 
tion and cultivation and appropriate fertilization, a yield of from I to 7 
or perhaps 8 tons per acre may be reasonably expected. It iadifticult 
to see, however, how it is possible for such yields as have been reported, 
viz, 40, 50, and even 60 tons per acre, to be gathered. In exceptional 
conditions, as in the case with all crops, exceptional yields may be 
obtained, but these must not be considered in the practical study of 
the problem of profitable production. 

The profit which the farmer may make from growing this crop, and 
the manufacturer from using it, should, in my opinion, be based upon 
a yield of 4 or 5 tons per acre. If it be desired to make starch from the 
plant, we may suppose as a minimum rate of yield that 20 per cent of 
the weight of the fresh root may be obtained as merchantable starch of 
a high grade. On a yield of 4 tons per acre this would amount to 
eight-tenths of a ton, or 1,600 pounds. Compare this with the weight 
of starch obtained from Indian corn producing 40 bushels per acre. 



16 

The yield of merchantable starch of a high grade may be placed at 35 
pounds per bushel, which, for 40 bushels would amount to 1,400 pounds. 
It is thus seen that the rate of yield per acre in the matter of starch 
from cassava would be fully equal if not superior to that from Indian 
corn. 

If the matter of the manufacture of glucose be considered the esti- 
mate is even more favorable. Our experiments have shown that after 
the removal of the bark the whole root may be rasped and treated 
directly for the manufacture of glucose, either by inversion with dias- 
tase or by treating with dilute sulphuric acid. In the latter case not 
only were the starch and sugar present in the root obtained as glucose, 
but also a considerable quantity of the digestible liber. It is not an 
extravagant statement, therefore, to suppose that fully 30 j)er cent, on 
the weight of the fresh root, could be obtained as commercial glucose. 
This would give a yield per acre of 1.2 tons, or 2,400 pounds. These 
statements are made, of course, subject to the jiractical determinations 
of the manufacturer of glucose and starch from this ]>laut. Attempts 
have already been made in the manufacture of starch, but of course 
the full development of this industry must await the investment 
of capital and the necessary adjustment of new machinery to new 
processes. 

The object of the present bulletin is simply to point out the possi- 
bilities of the culture of cassava, not only for the farmer of Florida but 
also for the manufacturer and merchant. 

In its preparation Mr. E. E. Ewell has conducted the chemical and 
^preparatory work and Mr. G. L. Spencer has taken the i)hotographs. 

CONCLUSIONS. 

(1) Cassava can be cultivated with safety and profit in the greater 
part of the j)eniiisula of Florida, and probably also in southern Ala- 
bama, Mississippi, Louisiana, and Texas. 

(2) It will yield with fair treatment on the sand soils from 4 to 5 
tons i^er acre. 

(3) It will give, when properly manufactured, from 20 to 25 per cent 
of the weight of the fresh root in starch of high grade. 

(4) The starch is naturally in a pure state and no chemicals of any 
kind are necessary in its manufacture. 

(5) The starch resembles in its j)hysical properties the starch of 
maize and can be used as a substitute therefor in all cases. 

(6) An excellent article of tapioca can be prepared from the starch 
of the cassava plant. 

(7) Glucose can be prepared directly from the starch or more profit- 
ably from the pulp of the peeled root. 

(8) The plant furnishes an excellent human and cattle food, defi- 
cient, however, in nitrogen. It would make a well-balanced ration for 
cattle when mixed with one-fourth its weight of cotton seed oil cake. 



m 



